Analysis of aero-thermodynamic behavior of expert capsule in transitional regime

The aerodynamic behavior of the EXPERT capsule has been already widely studied at low altitudes. In order to broaden the aerodynamic data base of the capsule, additional computations of the aerodynamic forces and an evaluation of the longitudinal stability and fluctuation of the pressure center have been carried out in the altitude interval 80-105 km. The effect of the rolling angle has been also evaluated. As EXPERT, in the considered altitude interval is in transitional regime, computations have been made by the DSMC code DS3V. Heat flux along the capsule surface has been also evaluated. This is an important topic because the nose and the frustum are made of low and high catalyticity materials, respectively. Computations, already performed in continuum regime by the CFD code H3NS, showed that, at the nose-frustum junction, an abrupt and strong peak of heat flux is present. In this work, this problem has been analyzed also in transitional regime. For this application, the DSMC 2-D code DS2V, requiring smaller computer resources, compared with the ones required by DS3V, has been used for making computations at lower altitudes. Furthermore, using DS2V made possible also to get a more detailed definition of the body surface and therefore to increase the surface resolution. The launch of the capsule is currently scheduled in 2011; flight data should be available to verify the results of the present computations.